How do you get to Lt Surge in soul silver?

Goto bill (The pokemaniac) who owns the Pokemon storage system, obtain the SS Anne ticket from him.

Go onto the SS Anne ship and find the captain, talk to him to obtain the "Cut" HM02.

Teach this to a Pokemon, (Grass types like scyther, bellsprout etc are best)

Then go up the the bush blocking the entrance, press "Start" and goto Pokemon, select the Pokemon you have with "Cut" and use it whilsts facing the bush. It will cut it out the way allowing you to access the gym.

Once inside the gym, you must go around each bin and find a switch, one you press the first switch, save the game.

Then the next switch is in one of the bins next to the bin you found the first switch.

If you fail and get an incorrect bin and it resets the lock, just simply reset your gameboy or emulator and reload and try a different bin until you get the right one.

Hope this helps!
you have to turn on two switches in all of the 15 buckets of trash